JP2016054668A - Method of preparing culture solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a culture solution in which sodium ions are sufficiently removed, and a fertilizer component is contained without wasting it by using an electrolytic water produced using a non-diaphragm type electrolytic device instead of an RO device.SOLUTION: The present invention relates to the method of preparing the culture solution for cultivating plants, comprising: a step(P1) of adjusting acidic water from water to be treated by using the non-diaphragm type electrolytic apparatus having an ion adsorptive electrode and a counter electrode; a step(P2) of adjusting pH by adding an alkaline pH adjusting agent including the fertilizer component in the adjusted acidic water; and a step(P3) of adjusting the fertilizer concentration by adding the fertilizer to the pH-adjusted solution.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a cultivation nutrient solution for growing plants.

Conventionally, it is known that salts contained in water hinder the growth of plants. Especially, when the density | concentration of a sodium ion (Na ^<+> ) is high, the bad influence which has on growth is large. Therefore, what remove | eliminated salt and ion from tap water, groundwater, etc. using desalination apparatuses, such as RO (Reverse Osmosis: reverse osmosis membrane) apparatus, is used as agricultural water (for example, patent document 1). . Hereinafter, in the present specification, water artificially supplied to grow plants is defined as agricultural water, and water containing nutrients obtained by adding fertilizer to agricultural water is defined as cultivation nutrient solution.

  In recent years, in agriculture, hydroponics that cultivates plants without using soil is performed, and there are plant factories equipped with large-scale hydroponic systems. Hydroponics attracts attention because plants can be cultivated with a small amount of water even in dry areas such as deserts where farming is impossible. For example, in Patent Document 2, in hydroponics, by using electrolyzed water having a sodium ion concentration of 200 ppm or less and a pH in the range of 4.5 to 6.8, there is an adverse effect on plant growth at low cost. It is described that plants can be cultivated without giving. Moreover, not only hydroponic cultivation but conventionally, it is said that weakly acidic to neutral water is more suitable for plant cultivation than alkaline.

  On the other hand, for the purpose of controlling plant diseases, it has also been conventionally practiced to spray an acidic aqueous solution or an acidic electrolyte on plants. For example, Patent Document 3 describes a method and apparatus for adjusting spray water for plants provided with a diaphragm-type electrolyzer. In this method and apparatus, water is electrolyzed using an electrolysis apparatus having an ion adsorption electrode containing a conductive substance capable of reversibly adsorbing ions and a counter electrode, thereby adjusting acidic or alkaline spray water.

  As an electrolysis apparatus, there is a diaphragm type using a diaphragm such as an ion exchange membrane. However, the diaphragm type requires maintenance of the membrane and generates both acidic water and alkaline water. Therefore, there is a problem that either the acidic water or the alkaline water which is not desired becomes waste water, and a lot of waste water comes out. On the other hand, the non-diaphragm type using no diaphragm does not require maintenance of the diaphragm, but can selectively generate (adjust) only one of acidic water or alkaline water. However, in order to clean the ion adsorption electrode, it is necessary to release ions adsorbed on the ion adsorption electrode (cation in the case of acidic water, anion in the case of alkaline water) into the water. Although it becomes waste water, very little is required.

  In addition, in Patent Document 3, by adding a salt (for example, potassium chloride) containing ions necessary for the growth of crops to water before electrolytic treatment, the pH adjustment speed is increased, and the spray water is added. Techniques that also serve as a fertilizer are also described.

Japanese Laid-Open Patent Publication No. 01-304823 (released December 08, 1989) Japanese Patent Laid-Open No. 11-289892 (published on October 26, 1999) JP 2011-131118 A (released on July 07, 2011)

  However, the conventional techniques as described above have the following problems in cultivating a plant in an area with little water.

  The RO device does not obtain the entire amount of supplied water as treated water unlike a normal filter, and always generates waste water containing salt and ions at a high concentration. Therefore, in the method using the RO device, the ratio of waste water to water that can be used as agricultural water is high, and it is difficult to use it in an area with little water. Further, in the RO apparatus, it is necessary to apply a high pressure during operation, and a stable high-voltage power supply infrastructure is required to apply the high pressure. In addition, maintenance of the reverse osmosis membrane is also necessary.

  Moreover, the electrolyzed water used by the hydroponics method of patent document 2 adds hydrochloric acid to the water which does not contain sodium chloride, it is made hydrochloric acid addition water, this is passed through a non-diaphragm type electrolytic tank, and is electrolyzed, This is obtained by diluting with water and adjusting the pH to the range of 4.5 to 6.8. Therefore, when sodium chloride is contained in water to which hydrochloric acid is added or water to be diluted, it is necessary to desalinate using an RO device or the like. That is, even in the hydroponics method of Patent Document 2, when sodium chloride is contained in the water itself, it is necessary to remove this, and when the RO device is used for the removal, there is a problem similar to the above. .

  On the other hand, the adjusting device for adjusting the spray water of Patent Document 3 adjusts the pH of the spray water to be acidic or alkaline. Acidic or alkaline spray water is used to control plant pests. However, no consideration is given to the use of such an adjusting device for the production (adjustment) of agricultural water in place of the RO device described above.

  More specifically, Patent Document 3 discloses that water prior to electrolytic treatment includes hydrochlorides such as potassium chloride, sodium chloride, magnesium chloride, sulfates such as potassium sulfate sodium sulfate, magnesium sulfate, phosphates, nitrates, Proposals have been made to add salt such as organic acid salts and mixtures thereof so that the sprayed water also serves as a fertilizer. By using potassium-containing salts, it is possible to spray potassium together with pest control, and the addition of salt is desirable because the three major nutrients of nitrogen, phosphorus and potassium are essential for crop growth. It is described.

  However, when acidic spray water is adjusted by the procedure described in Patent Document 3, the relative concentration of sodium ions to be removed is reduced by cations such as potassium, which is a fertilizer added before electrolytic treatment. Therefore, sodium ions cannot be effectively removed by adsorption. Further, there is a problem that the cation of the fertilizer added before the electrolytic treatment is adsorbed by the ion adsorption electrode during electrolysis and discharged from the liquid.

  In the present invention, by using electrolyzed water generated by using a diaphragm-type electrolyzer instead of the RO device, sodium ions can be sufficiently removed and fertilizer components can be contained without wasting. The cultivation nutrient solution preparation method is provided.

  In order to solve the above problems, a cultivation nutrient solution preparation method according to one embodiment of the present invention is a method of preparing a cultivation nutrient solution for growing a plant, and includes an ion-adsorbing electrode and a counter electrode. The step of adjusting acidic water from the water to be treated using an electrolyzer having no diaphragm, the step of adjusting the pH by adding an alkaline pH adjuster containing a fertilizer component to the adjusted acidic water, and adjusting the pH Adding a fertilizer to the liquid and adjusting the fertilizer concentration.

  According to one aspect of the present invention, sodium ions are sufficiently removed using electrolyzed water generated by using a diaphragm-type electrolyzer instead of the RO device, and the fertilizer component is not wasted. There exists an effect that the cultivation culture solution made to contain can be produced.

It is process drawing of the cultivation nutrient solution preparation method which concerns on one Embodiment of this invention. It is a schematic diagram which shows the structure of the cultivation nutrient solution preparation system to which the said cultivation nutrient solution preparation method is applied. It is a schematic diagram which shows the structure of the electrolyzer in the said cultivation nutrient solution preparation system. It is a graph which shows the relationship between pH and an electrical conductivity (EC) at the time of using the case where a pH down agent (acidic pH adjuster) is used, and the said electrolysis apparatus. It is a graph which shows the result of having investigated the relationship between the density | concentration of the sodium ion which remains in a liquid, and the density | concentration of the potassium ion which replaced the adsorbed sodium ion.

[Embodiment 1]
Hereinafter, embodiments of the present invention will be described in detail. In the following description, embodiments of the present invention will be described by way of examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values and specific materials may be exemplified, but other numerical values and other materials may be applied as long as the effect of the present invention is obtained.

FIG. 1 is a process diagram of the cultivation nutrient solution preparation method of the present embodiment. In a 1st process (P1), to-be-processed water is electrolyzed using the electroless apparatus of a diaphragm type which has an ion adsorption electrode and a counter electrode, and acidic water is adjusted. Specifically, cations in the water to be treated are adsorbed on the ion adsorption electrode. Since sodium ions that adversely affect plant growth are also cations, they are adsorbed and removed from the water to be treated. The counter electrode electrolyzes water (H ₂ O) that is water to be treated. As a result of the electrolysis of water, oxygen gas and hydrogen ions (H ⁺ ) are generated. As a result, the pH of the water to be treated is lowered to become acidic water.

  As the water to be treated, tap water, ground water, rain water, pond water, river water, water obtained by desalinating seawater, or mixed water containing at least two of these can be used.

In the second step (P2), an alkaline pH adjuster containing fertilizer component ions is added to the acid water adjusted in the first step (P1) to adjust to a target pH suitable for the plant to be cultivated. Examples of fertilizer component ions include potassium ions (K ⁺ ), calcium ions (Ca ²⁺ ), and magnesium ions (Mg ²⁺ ). Examples of alkaline pH adjusters containing these ions include potassium hydroxide (KOH), calcium hydroxide (Ca (OH) ₂ ), magnesium hydroxide (Mg (OH) ₂ ), and the like. In the first step (P1), the cation of the fertilizer component is replaced and contained in place of the cation such as the removed sodium ion.

  In addition, this 2nd process (P2) is not an essential process, and is unnecessary when the pH of the acidic water adjusted by the 1st process (P1) is suitable for the plant to grow or a cultivation process. Moreover, when performing pH adjustment, it is not essential to use the pH adjuster containing a fertilizer component, and you may use the pH adjuster which does not contain a fertilizer component.

  In a 3rd process (P2), a fertilizer is added to the liquid which adjusted pH by the 2nd process (P2), and a fertilizer density | concentration is adjusted. The liquid in which the fertilizer concentration is adjusted becomes the cultivation nutrient solution. The fertilizer added to the liquid is an essential element of a plant such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg). The fertilizer concentration is adjusted by measuring the electrical conductivity (EC) of the liquid to which the fertilizer is added and adjusting the electrical conductivity to a target value.

  Although not shown, as a post-process or a pre-process of the first step (P1), a cleaning process is performed to release cations adsorbed on the ion adsorption electrode into water. As water for releasing cations, water to be treated can be used. The water from which cations are released becomes waste water, but the amount thereof is extremely small compared to the amount of acid water to be adjusted, and can be used without any problem even in an area with little water.

  Drawing 2 is a mimetic diagram showing composition of cultivation nutrient solution preparation system 1 to which a cultivation nutrient solution preparation method of this embodiment is applied. The cultivation nutrient solution preparation system 1 includes an acidic water tank 2 that stores acidic water, a cultivation nutrient solution tank 4 that stores cultivation nutrient solution, an electrolysis device 8 that adjusts treated water to acidic water, and a sensor unit 6. 7 etc. The sensor units 6 and 7 include an EC sensor that measures the electrical conductivity of the liquid in the tanks 2 and 4, a pH sensor that measures the pH of the liquid, a sodium ion concentration sensor that specifies the sodium ion concentration of the liquid, and the like. include.

  The acidic water tank 2 is supplied with tap water, groundwater, rainwater, etc. as treated water. The electrolyzer 8 is connected to the acidic water tank 2 in a circulating manner. The liquid in the acidic water tank 2 is sent to the electrolyzer 8 to remove cations such as sodium ions and acidify, and then returned to the acidic water tank 2 again. The water to be treated which is a liquid in the acidic water tank 2 is gradually acidified while being circulated between the acidic water tank 2 and the electrolyzer 8 and adjusted to acidic water. In the present embodiment, when the pH of the liquid (acid water) in the acid water tank 2 reaches the set value, it is determined that the adjustment of the acid water is complete, and the liquid (acid water) in the acid water tank 2 is It is moved to the cultivation nutrient tank 4.

  The cultivation nutrient solution tank 4 is supplied with a pH adjuster and a fertilizer. First, the pH adjusting agent is supplied until the pH of the liquid (acidic water) in the cultivation nutrient tank 4 reaches a pH suitable for the plant to be cultivated. When the plant to be cultivated is watermelon, strawberry, cabbage or the like, mild acidity having a relatively low pH is suitable.

  When the pH of the liquid in the cultivation nutrient tank 4 reaches the set value, then fertilizer is supplied. While monitoring the electrical conductivity, the fertilizer concentration is adjusted to be suitable for the plant to be cultivated.

  FIG. 3 is a schematic diagram showing a configuration of the electrolysis apparatus 8 in the cultivation nutrient solution preparation system 1. As shown in FIG. 3, the electrolysis apparatus 8 is a diaphragm type, and applies a voltage to the treatment tank 10 for treating the water to be treated, the electrode group 12 disposed in the treatment tank 10, and the electrode group 12. Power supply 14. The electrode group 12 includes an ion adsorption electrode 12a containing a conductive substance capable of reversibly adsorbing ions and a counter electrode 12b. As a preferred example of the electrode group 12, in the configuration of FIG. 3, a plurality of plate-like ion adsorption electrodes 12a and a plurality of plate-like counter electrodes 12b are alternately arranged in parallel.

  The ion adsorption electrode 12a includes a conductive substance A capable of reversibly adsorbing ions. The conductive substance A is a substance capable of reversibly adsorbing and releasing ions, and includes, for example, a carbon material such as activated carbon or graphite.

  The counter electrode 12b is, for example, a metal electrode. A preferred example of the counter electrode 12b is an electrode on the surface of which a metal (for example, platinum) that easily causes electrolysis of water exists. As the counter electrode 12b, for example, an electrode made of titanium, an electrode made of platinum, or the like can be used.

  The power supply 14 is a power supply (DC power supply) for applying a voltage (DC voltage) between the ion adsorption electrode 12a and the counter electrode 12b. The power source may be an AC-DC converter that converts an AC voltage from an outlet into a DC voltage. The power source may be a power generation device such as a solar cell or a fuel cell, or a secondary battery.

  The power supply 14 and the electrode group 12 are connected via a conductive material 18 and a wiring 16, and the polarity applied to the ion adsorption electrode 12 a and the counter electrode 12 b is alternatively switched by a switch 15. It is like that.

  As a preferred example, in the configuration of FIG. 3, an inflow path 20 from the acidic water tank 2 is connected to the lower part of the processing tank 10, and an outflow path 22 to the acidic water tank 2 is connected to the upper part of the processing tank 10. Has been. By setting the flow of the water to be treated from the bottom to the top as shown by the arrow 24, the gas generated on the surfaces of the electrodes 12a and 12b can be quickly discharged from the upper part of the treatment tank 10.

  In such an electrolysis apparatus 8, in the first step (P1) of adjusting the water to be treated to acidic water, a voltage is applied so that the ion adsorption electrode 12a becomes a cathode and the counter electrode 12b becomes an anode. Thereby, in ion adsorption electrode 12a (cathode), cations (for example, cations other than hydrogen ion) in to-be-processed water are adsorbed by conductive substance A of ion adsorption electrode 12a. Sodium ions that adversely affect plant growth are also adsorbed by the conductive substance A. On the other hand, in the counter electrode 12b, the water to be treated is electrolyzed to generate oxygen gas and hydrogen ions. The electrolytic treatment of the water to be treated may be either a flowing water method performed while flowing the water to be treated or a batch method performed by stopping the flow of the water to be treated.

  In the cleaning process performed as a pre-process or post-process of the first process, a voltage is applied so that the ion adsorption electrode 12a serves as an anode and the counter electrode 12b serves as a cathode. Thereby, the cation adsorbed by the ion adsorption electrode 12a is released into water. The cleaning process is performed in a batch manner, and waste water that is a liquid from which cations are released is discarded without being returned to the acidic water tank 2.

  The voltage applied between the ion adsorption electrode 12a and the counter electrode 12b is not particularly limited as long as it is a voltage that causes water electrolysis in the counter electrode 12b. In one example, the applied voltage is in the range of 3 to 30 volts. When applying a voltage, a constant voltage may be applied, or a voltage may be applied so that a constant current flows between the electrodes. Further, the pH or sodium ion concentration of the prepared acidic water may be monitored, and the voltage may be changed according to the pH or sodium ion concentration.

  FIG. 4 is a graph showing the relationship between pH and electrical conductivity (EC) when using a pH-lowering agent (acidic pH adjusting agent) and when acid water is used in the electrolysis apparatus 8. As shown in FIG. 4, when the water to be treated having a pH of 8 and an electric conductivity of 0.2 mS / cm was converted to acidic water using a pH dung agent, the electric conductivity increased as the pH was lowered. This is because the amount of ions in the liquid increases as the added amount of the pH dung agent increases. On the other hand, when acid water was used in the electrolyzer 8, the electrical conductivity decreased due to a decrease in cations in the liquid, and decreased by about 25% at pH 5.5. This means that the electrical conductivity at pH 5.5 could be reduced by 45% compared to the case where it was used with a pH down agent. The low electrical conductivity of water before adding fertilizers in this way indicates a state close to pure water. Therefore, in addition of the fertilizer in a subsequent process, adjustment to a fertilizer concentration suitable for the growth of the plant to be cultivated becomes easy.

The amount of waste water (water generated in the cleaning process) when pH 5.5 acidic water was obtained was about 10% with respect to the produced acidic water, and no high-voltage current was required. Further, when the component variation of acid water adjusted by the electrolyzer 8 (component variation from the water to be treated) was examined, the sodium ion decreased by 49% from 18.8 ppm to 9.5 ppm, whereas the chloride ion It was confirmed that (Cl ⁻ ) decreased by 5% and hardly changed.

  FIG. 5 is a graph showing the results of examining the relationship between the concentration of sodium ions remaining in the treated liquid and the concentration of potassium ions replaced with the adsorbed sodium ions. As shown in FIG. 5, the fewer sodium ions adsorbed and the higher the sodium ion concentration in the liquid (sample 1), the lower the concentration of potassium ions, and the lower the concentration. When the sodium ion adsorption amount increases and the sodium ion concentration in the liquid decreases, the amount of potassium ions that are replaced increases, and the potassium ion concentration in the liquid increases (sample 4).

  From this, it can be seen that when the sodium ion concentration of the water to be treated is high, it is effective to strongly acidify and lower the sodium ion concentration and replace with cations of essential elements such as potassium ions.

  In addition, since it is performed while monitoring the electrical conductivity and pH of the water to be treated, there is an advantage that it is easy to cope with fluctuations in the electrical conductivity and pH of the water to be treated depending on the season.

  The cultivation nutrient solution is not limited to hydroponics, but can also be applied to nutrient solution cultivation using soil as a medium, and can also be used when planting and cultivating plants in soil in addition to plant factories and house cultivation.

[Embodiment 2]
The cultivation nutrient solution preparation method according to another embodiment of the present invention is different from the first embodiment in the criteria for determining that the adjustment of the acidic water is completed in the step of adjusting the acidic water in the first step (P1). In the first embodiment, the completion of the adjustment of the acid water is determined based on the pH of the liquid (acid water) in the acid water tank 2. On the other hand, in this Embodiment, completion of adjustment of acidic water is judged based on the sodium ion concentration of the liquid (acidic water) in the acidic water tank 2. FIG. Since sodium ions adversely affect the growth of plants, it is preferable to determine the completion of adjustment of acidic water based on the sodium ion concentration from the viewpoint of removing sodium ions.

[Embodiment 3]
In the cultivation nutrient solution preparation method according to another embodiment of the present invention, in the step of adjusting the acidic water in the first step (P1), the criteria for determining that the adjustment of the acidic water is completed are the first and second embodiments. Is different. In the first embodiment, the completion of the adjustment of the acidic water is determined based on the pH of the liquid (acidic water) in the acidic water tank 2 and in the second embodiment, based on the sodium ion concentration. On the other hand, in this Embodiment, the electrical conductivity of the liquid (acidic water) in the acidic water tank 2 judges completion of adjustment of acidic water based on the electrical conductivity of to-be-processed water. Even if there is no pH sensor or sodium ion concentration sensor, it is possible to judge the completion of the adjustment of the acidic water by using the EC sensor used for adjusting the fertilizer concentration and comparing it with the electrical conductivity of the water to be treated before the treatment. .

[Embodiment 4]
The cultivation nutrient solution preparation method of other embodiment of this invention measures the electrical conductivity of the to-be-processed water in the acidic water tank 2 before electrolyzing with the electrolysis apparatus 8, and is electrically with tap water etc. as to-be-processed water. When using water with high conductivity, the point which mixes and uses water whose electrical conductivity, such as rain water, is lower than tap water differs.

  When the electrical conductivity of to-be-processed water is high, the electrical conductivity of the cultivation nutrient solution after a 3rd process (P3) process becomes high. When the electrical conductivity of the cultivation nutrient solution is high, water with low electrical conductivity is mixed and diluted so that the electrical conductivity is in a range suitable for the plant to be cultivated and the cultivation process. However, in that case, the pH adjusted in the second step (P2) changes depending on the water used for dilution, and it is necessary to adjust the pH again in order to obtain a cultivation nutrient solution having a desired pH.

  On the other hand, when the electrical conductivity of the liquid to be treated used in the first step (P1) is high as in the present embodiment, the final pH adjustment is facilitated by lowering in advance.

  In addition, although the range of the electrical conductivity preferable as to-be-processed water is 0.05-5.0 mS / cm, although it depends on the kind of cultivation crop and a cultivation process. If the electrical conductivity exceeds the range, the electrical conductivity will be higher than the appropriate range for cultivation. On the other hand, when the electrical conductivity is low beyond the above range, there are many cases where adjustment of agricultural water is not necessary, and there is a problem that it takes time for electrolysis and adjustment of acidic water.

[Summary]
The cultivation nutrient solution preparation method which concerns on 1 aspect of this invention is a method of producing the cultivation nutrient solution for cultivating a plant, Comprising: The non-diaphragm which has an ion-adsorbing electrode (12a) and a counter electrode (12b) And a step of adjusting acid water from the water to be treated using the electrolytic device (8) of the formula, and a step of adjusting the fertilizer concentration by adding the fertilizer to the liquid whose pH is adjusted.

  According to said method, it can mix | blend water and a fertilizer component almost without wasting | dissolving using the electrolyzed water produced | generated using the electrolyzer of a diaphragm type instead of RO apparatus, and it is from moderately acidic to medium Sexual cultivation nutrient solution can be prepared.

  In other words, when fertilizers that become cations such as potassium are added to the water to be treated before electrolysis to make acidic water, the relative concentration of sodium ions to be removed decreases, and sodium ions are efficiently removed. It cannot be removed by adsorption. Further, there is a problem that the cation of the fertilizer added before the electrolytic treatment is adsorbed by the ion adsorption electrode during electrolysis and discharged from the liquid. However, by adding after electrolytic treatment in this way, sodium ions can be efficiently removed, and fertilizer components such as potassium can be contained without being wasted.

  Furthermore, the cultivation nutrient solution preparation method which concerns on 1 aspect of this invention adds the alkaline pH adjuster containing a fertilizer component between the said process which adjusts acidic water, and the said process which adjusts a fertilizer density | concentration. It is good also as a structure including the process of adjusting pH of acidic water.

  When electrolysis performed to remove sodium ions results in acidic water and the pH becomes too low, it can be adjusted to a desired pH by adjusting with an alkaline pH adjuster. Moreover, at that time, by using a pH adjuster containing a fertilizer component, the liquid after the pH adjustment has harmful sodium ions while maintaining the same electrical conductivity and pH as the water to be treated before the acid water. It is also possible to use water that is replaced with a cation such as potassium, which is an essential element.

  Furthermore, the cultivation nutrient solution preparation method which concerns on 1 aspect of this invention is good also as a structure acidified until the sodium ion density | concentration in to-be-processed water becomes below a predetermined density | concentration in the said process to adjust the said acidic water.

  Since the purpose of producing acidic water is to remove sodium ions that adversely affect plant growth, judging the completion of adjustment of acidic water based on the sodium ion concentration ensures that the desired sodium ion concentration is reached. Can reduce salt.

  Furthermore, in the cultivation nutrient solution preparation method according to one aspect of the present invention, as the water to be treated, tap water, groundwater, rainwater, pond water, river water, water obtained by desalinating seawater, or mixed water containing at least two of these Is used.

  Furthermore, the cultivation nutrient solution preparation method which concerns on 1 aspect of this invention mixes and uses water with low electrical conductivity, when using water with high electrical conductivity as to-be-processed water.

  When the electrical conductivity of the water to be treated is high, the electrical conductivity of the cultivation nutrient solution obtained by adjusting the fertilizer concentration is high, so water with low electrical conductivity is mixed and diluted. However, in that case, the adjusted pH may vary depending on the pH of the water used for dilution, and it may be necessary to adjust the pH again.

  In the said structure, final pH adjustment becomes easy by lowering | hanging an electrical conductivity in the stage of to-be-processed water.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used for hydroponics using a culture nutrient solution in which fertilizer is dissolved in water.

DESCRIPTION OF SYMBOLS 1 Cultivation nutrient solution preparation system 2 Acidic water tank 4 Cultivation nutrient solution tanks 6 and 7 Sensor part 8 Electrolyzer 10 Treatment tank 12 Electrode group 12a Ion adsorption electrode 12b Counter electrode 14 Power supply 15 Switch 16 Wiring 18 Conductive material 20 Inflow path 22 Outflow Road

Claims (5)

A method for producing a cultivation nutrient solution for cultivating a plant,
A step of adjusting acidic water from the water to be treated using a diaphragm-type electrolyzer having an ion-adsorbing electrode and a counter electrode;
adding fertilizer to the liquid with adjusted pH to adjust the fertilizer concentration;
The cultivation nutrient solution preparation method characterized by including this.   A step of adjusting the pH of the acidic water by adding an alkaline pH adjuster containing a fertilizer component between the step of adjusting the acidic water and the step of adjusting the fertilizer concentration is included. The cultivation nutrient solution preparation method of claim | item 1.   The cultivation nutrient solution preparation method according to claim 1 or 2, wherein in the step of adjusting the acid water, acidification is performed until a sodium ion concentration in the water to be treated is equal to or lower than a preset concentration.   The water to be treated is tap water, ground water, rain water, river water, pond water, water obtained by desalinating seawater, or mixed water containing at least two of these waters. Of cultivation nutrient solution preparation method.   When using water with high electric conductivity as said to-be-processed water, water with lower electric conductivity is mixed and used, The cultivation liquid preparation method of Claim 2 characterized by the above-mentioned.

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